Method, apparatus, and system for acquiring load information

ABSTRACT

The present invention discloses a method, an apparatus and a system for acquiring load information. In one method, a source access controller and a target access controller can interact through RAT handover related messages so that a source RAT system can acquire load information of a target RAT system when an inter-RAT PS handover is performed. This enables load balancing between different RAT systems so as to guarantee communications quality of the systems. In another method of the present invention, the source access controller and the target access controller interact through a RAN RIM based load information request message and an RIM based load information response message, so that the source RAT system can acquire load information of the target RAT system before an inter-RAT PS domain handover is performed. This enables load balancing between different RAT systems so as to guarantee the communications quality of the systems.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.13/235,891, filed on Sep. 19, 2011, which is a continuation ofInternational Application No. PCT/CN2009/070872, filed on Mar. 18, 2009.The afore-mentioned patent applications are hereby incorporated byreference in their entireties.

FIELD OF THE INVENTION

The present invention relates to the field of mobile communicationstechnologies, and in particular, to a method, an apparatus, and a systemfor acquiring load information.

BACKGROUND OF THE INVENTION

When a network develops toward a broadband and mobile system, a 3rdGeneration Partnership Project (3rd Generation Partnership Project 3GPP)proposes a Long Term Evolution (Long Term Evolution, LTE) solution,namely, an Evolved Universal Mobile Telecommunication System TerrestrialRadio Access Network (Evolved Universal Mobile Telecommunication SystemTerrestrial Radio Access Network, E-UTRAN), for a mobile access network,and a System Architecture Evolution (System Architecture Evolution, SAE)solution, namely, an Evolved Packet Core (Evolved Packet Core, EPC), fora mobile core network. In LTE/SAE architecture, because some operatorsexpect that, after an Evolved Packet System (Evolved Packet System, EPS)network is deployed, a voice service is still provided by a conventional2G/3G Radio Access Network (RAN) and a Circuit Switched (CircuitSwitched CS) domain core network while the EPS network provides onlyPacket Switched (Packet Switched, PS) domain data access, the EPSnetwork coexists with the conventional 2G/3G CS domain core network fora period of time. A User Equipment (User Equipment, UE) can access a CSdomain core network through a 2G/3G RAN such as a Global System forMobile Communications (Global System for Mobile Communications,GSM)/Enhanced Data Rate for GSM Evolution (Enhanced Data Rate for GSMEvolution, EDGE) Radio Access Network (Radio Access Network, GERAN) or aUniversal Mobile Telecommunication System Terrestrial Radio AccessNetwork (Universal Mobile Telecommunication System Terrestrial RadioAccess Network, UTRAN), and access the EPC through the E-UTRAN.

To balance loads between RANs, namely, Radio Access Technology (RadioAccess Technology, RAT) systems, an inter-RAT handover is supported.When a UE performs a CS domain handover between 2G/3G RAT systems, asource access controller to which a source cell belongs in a source RATsystem can interact with an access controller to which a target cellbelongs in a target RAT system through a RELOCATION REQUIRED message,and a RELOCATION COMMAND message or a RELOCATION PREPARATION FAILUREmessage.

In the above technical solutions, when an inter-RAT PS domain handoveris performed or before an inter-RAT CS or PS domain handover isperformed, the source RAT system is unable to acquire the loadinformation of the target RAT system, so that inter-RAT load balancingfails to be implemented. As a result, communications quality of thesystems fails to be guaranteed.

SUMMARY OF THE INVENTION

Embodiments of the present invention provide a method, an apparatus, anda system for acquiring load information to enable a source RAT system toacquire load information of a target RAT system, so that inter-RAT loadbalancing can be implemented to guarantee communications quality of thesystems.

An embodiment of the present invention provides a method for acquiringload information. The method includes:

when an inter-RAT PS domain handover is performed, sending, through acore network, by a source access controller to which a source cellbelongs, an inter-RAT handover request message to a target accesscontroller to which serves a target cell belongs; and

receiving, by the source access controller, an inter-RAT handoverresponse message returned by the target access controller according tothe inter-RAT handover request message through the core network, wherethe inter-RAT handover response message carries load information of thetarget cell.

An embodiment of the present invention provides another method foracquiring load information. The method includes:

before an inter-RAT handover is performed, sending, through a corenetwork, by a source access controller to which a source cell belongs, aRAN Information Management (RAN Information Management, RIM) based loadinformation request message to a target access controller to which atarget cell belongs; and

receiving, by the source access controller, an RIM based loadinformation response message returned by the target access controlleraccording to the RIM based load information request message through thecore network, where the RIM based load information response messagecarries load information of the target cell.

An embodiment of the present invention provides an access controller.The access controller includes:

a first sending module, configured to send, through a core network, aninter-RAT handover request message to a target access controller towhich a target cell belongs when an inter-RAT PS domain handover isperformed; and

a first receiving module, configured to receive an inter-RAT handoverresponse message returned by the target access controller according tothe inter-RAT handover request message through the core network, wherethe inter-RAT handover response message carries load information of thetarget cell.

An embodiment of the present invention provides another accesscontroller. The access controller includes:

a third sending module, configured to send, through a core network, anRIM based load information request message to a target access controllerto which a target cell belongs before an inter-RAT handover isperformed; and

a third receiving module, configured to receive an RIM based loadinformation response message returned by the target access controlleraccording to the RIM based load information request message through thecore network, where the RIM based load information response messagecarries load information of the target cell.

An embodiment of the present invention provides a system for acquiringload information. The system includes a first source access controllerto which a source cell belongs in a source RAT system and a first targetaccess controller to which a target cell belongs in a target RAT system,where:

the first source access controller is configured to send, through a corenetwork, an inter-RAT handover request message to the first targetaccess controller to which the target cell belongs when an inter-RAT PSdomain handover is performed, and receive an inter-RAT handover responsemessage returned by the first target access controller through the corenetwork, where the inter-RAT handover response message carries loadinformation of the target cell; and

the first target access controller is configured to receive theinter-RAT handover request message that is sent, through the corenetwork, by the first source access controller to which the source cellbelongs, and return the inter-RAT handover response message to the firstsource access controller through the core network.

An embodiment of the present invention provides another system foracquiring load information. The system includes a second source accesscontroller to which a source cell belongs in a source RAT system and asecond target access controller to which a target cell belongs in atarget RAT system, where:

the second source access controller is configured to send, through acore network, an RIM based load information request message to thesecond target access controller to which the target cell belongs beforean inter-RAT handover is performed, and receive an RIM based loadinformation response message returned by the second target accesscontroller through the core network, where the RIM based loadinformation response message carries load information of the targetcell; and

the second target access controller is configured to receive the RIMbased load information request message that is sent, through the corenetwork, by the second source access controller to which the source cellbelongs, and return the RIM based load information response message tothe second source access controller through the core network.

According to the above technical solutions, the source access controllerand the target access controller in the embodiments of the presentinvention can interact through inter-RAT handover related messages sothat the source RAT system can acquire load information of the targetRAT system when an inter-RAT PS domain handover is performed andtherefore load balancing between different RAT systems can beimplemented. This guarantees communications quality of the systems. Thesource access controller and the target access controller in theembodiments of the present invention can also interact through an RIMbased load information request message and an RIM based load informationresponse message, so that the source RAT system can acquire loadinformation of the target RAT system before an inter-RAT handover isperformed and therefore inter-RAT load balancing can be implemented.This guarantees the communications quality of the systems.

BRIEF DESCRIPTION OF THE DRAWINGS

To better explain the technical solutions of the present invention, theaccompanying drawings required in the description of the embodiments ofthe present invention or the prior art are briefly described. It isapparent that the accompanying drawings illustrate only some exemplaryembodiments of the present invention. Those skilled in the art canderive other drawings from these drawings without any creative effort.

FIG. 1 is a schematic flowchart of a method for acquiring loadinformation according to a first embodiment of the present invention;

FIG. 2 is a schematic flowchart of a method for acquiring loadinformation according to a second embodiment of the present invention;

FIG. 3 is a schematic flowchart of a method for acquiring loadinformation according to a third embodiment of the present invention;

FIG. 4 is a schematic flowchart of a method for acquiring loadinformation according to a fourth embodiment of the present invention;

FIG. 5 is a schematic flowchart of a method for acquiring loadinformation according to a fifth embodiment of the present invention;

FIG. 6 is a schematic flowchart of a method for acquiring loadinformation according to a sixth embodiment of the present invention;

FIG. 7 is a schematic flowchart of a method for acquiring loadinformation according to a seventh embodiment of the present invention;

FIG. 8 is a schematic flowchart of another method for acquiring loadinformation according to an eighth embodiment of the present invention;

FIG. 9 is a schematic flowchart of another method for acquiring loadinformation according to a ninth embodiment of the present invention;

FIG. 10 is a schematic flowchart of another method for acquiring loadinformation according to a tenth embodiment of the present invention;

FIG. 11 is a schematic flowchart of another method for acquiring loadinformation according to an eleventh embodiment of the presentinvention;

FIG. 12 is a schematic flowchart of another method for acquiring loadinformation according to a twelfth embodiment of the present invention;

FIG. 13 is a schematic flowchart of another method for acquiring loadinformation according to a thirteenth embodiment of the presentinvention;

FIG. 14 is a schematic flowchart of another method for acquiring loadinformation according to a fourteenth embodiment of the presentinvention;

FIG. 15 is a schematic structural diagram of an access controlleraccording to a fifteenth embodiment of the present invention;

FIG. 16 is a schematic structural diagram of another access controlleraccording to a sixteenth embodiment of the present invention;

FIG. 17 is a schematic structural diagram of still another accesscontroller according to a seventeenth embodiment of the presentinvention;

FIG. 18 is a schematic structural diagram of still another accesscontroller according to an eighteenth embodiment of the presentinvention;

FIG. 19 is a schematic structural diagram of a system for acquiring loadinformation according to a nineteenth embodiment of the presentinvention; and

FIG. 20 is a schematic structural diagram of another system foracquiring load information according to a twentieth embodiment of thepresent invention.

DETAILED DESCRIPTION OF THE EMBODIMENTS

To better explain the technical solutions of the present invention, theembodiments of the present invention are described in detail withreference to the accompanying drawings. It is apparent that theembodiments herein are only some exemplary embodiments of the presentinvention. Based on the embodiments of the present invention, thoseskilled in the art can derive other embodiments without any creativeeffort and such other embodiments all fall into the protection scope ofthe present invention.

For a description purpose, load information of a target cell in a targetRAT system is herein referred to as load information of the target RATsystem. Likewise, load information of a source cell in a source RATsystem is referred to as load information of the source RAT system.

FIG. 1 is a flowchart of a method for acquiring load informationaccording to a first embodiment of the present invention. As shown inFIG. 1, the method for acquiring load information in this embodiment mayinclude the following steps:

Step 101: When an inter-RAT PS domain handover is performed, a sourceaccess controller to which a source cell belongs in a source RAT systemsends, through a core network, an inter-RAT handover request message toa target access controller to which a target cell belongs in a targetRAT system.

Step 102: The source access controller receives an inter-RAT handoverresponse message returned by the target access controller according tothe inter-RAT handover request message through the core network, wherethe inter-RAT handover response message carries load information of thetarget cell.

The source RAT system and the target RAT system in this embodiment maybe any two systems of a GERAN, a UTRAN, and an E-UTRAN. Thecorresponding access controllers are respectively a Base Station System(Base Station System, BSS), a Radio Network Controller (Radio NetworkController, RNC), or an evolved NodeB (evolved NodeB, eNB).

In this embodiment, the bearing of the load information of the targetcell may be implemented by a Transparent Container Information Element(Information Element, IE) carried in the inter-RAT handover relatedmessages.

In this embodiment, the source access controller and the target accesscontroller interact through the inter-RAT handover related messages. Inthis way, when an inter-RAT PS domain handover is performed, the sourceRAT system can acquire the load information of the target RAT system, sothat load balancing can be implemented between different RAT systems.Therefore, communications quality of the systems can be guaranteed.

An inter-RAT PS domain handover between any two of the preceding RATsystems is performed. Access controllers in different RAT systems eachinteract with the core network through different handover relatedmessages. The specific procedures are described in detail in thefollowing six exemplary embodiments of the present invention.

FIG. 2 is a schematic flowchart of a method for acquiring loadinformation according to a second embodiment of the present invention.As shown in FIG. 2, this embodiment is applicable to a PS domainhandover from a UTRAN to an E-UTRAN. The method for acquiring loadinformation in this embodiment may include the following steps:

Step 201: A source RNC to which a source cell belongs sends a RELOCATIONREQUIRED (RELOCATION REQUIRED) message to a Serving GPRS Support Node(Serving GPRS Support Node, SGSN), where the RELOCATION REQUIRED messagecarries a first Transparent Container IE that carries a source cell loadinformation IE.

Step 202: The SGSN receives the RELOCATION REQUIRED message and sends afirst HANDOVER REQUEST message to a target eNB to which a target cellbelongs, where the first HANDOVER REQUEST message carries the firstTransparent Container IE.

Step 203: The target eNB receives the first HANDOVER REQUEST message andreturns a HANDOVER REQUEST ACKNOWLEDGE message to the SGSN, where theHANDOVER REQUEST ACKNOWLEDGE carries a second Transparent Container IEthat carries a target cell load information IE.

Step 204: The SGSN receives the HANDOVER REQUEST ACKNOWLEDGE message andreturns a first RELOCATION COMMAND message to the source RNC, where thefirst RELOCATION COMMAND message carries the second TransparentContainer IE.

In this embodiment, the first Transparent Container IE may be anInter-System Information Transparent Container IE or a Source eNB ToTarget eNB Transparent Container IE. Likewise, the second TransparentContainer IE may be an Inter-System Information Transparent Container IEor a Target eNB To Source eNB Transparent Container IE.

In this embodiment, the load information of different RAT systems isexchanged through the source cell load information IE carried in thefirst Transparent Container IE and the target cell load information IEcarried in the second Transparent Container IE In this way, when aninter-RAT PS domain handover from the UTRAN to the E-UTRAN is performed,the UTRAN and the E-UTRAN can acquire load information of the peersystem, so that load balancing can be implemented between different RATsystems. Therefore, communications quality of the systems is guaranteed.

FIG. 3 is a schematic flowchart of a method for acquiring loadinformation according to a third embodiment of the present invention. Asshown in FIG. 3, this embodiment is applicable to a PS domain handoverfrom a UTRAN to a GERAN. The method for acquiring load information inthis embodiment may include the following steps:

Step 301: A source RNC to which a source cell belongs sends a RELOCATIONREQUIRED message to an SGSN, where the RELOCATION REQUIRED messagecarries a first Transparent Container IE that carries a source cell loadinformation IE.

Step 302: The SGSN receives the RELOCATION REQUIRED message and sends afirst PS-HANDOVER-REQUEST message to a target BSS to which a target cellbelongs, where the first PS-HANDOVER-REQUEST message carries the firstTransparent Container IE.

Step 303: The target BSS receives the first PS-HANDOVER-REQUEST messageand returns a PS-HANDOVER-REQUEST-ACKNOWLEDGE message to the SGSN, wherethe PS-HANDOVER-REQUEST-ACKNOWLEDGE message carries a second TransparentContainer IE that carries a target cell load information IE.

Step 304: The SGSN receives the PS-HANDOVER-REQUEST-ACKNOWLEDGE messageand returns a second RELOCATION COMMAND message to the source RNC, wherethe second RELOCATION COMMAND message carries the second TransparentContainer IE.

In this embodiment, the first Transparent Container IE may be anInter-System Information Transparent Container IE or a Source BSS ToTarget BSS Transparent Container IE. Likewise, the second TransparentContainer IE may be an Inter-System Information Transparent Container IEor a Target BSS To Source BSS Transparent Container IE.

In this embodiment, the load information of different RAT systems isexchanged through the source cell load information IE carried in thefirst Transparent Container IE and the target cell load information IEcarried in the second Transparent Container IE. In this way, when aninter-RAT PS domain handover from the UTRAN to the GERAN is performed,the UTRAN and the GERAN can acquire load information of the peer system,so that load balancing can be implemented between different RAT systems.Therefore, the communications quality of the systems is guaranteed.

FIG. 4 is a schematic flowchart of a method for acquiring loadinformation according to a fourth embodiment of the present invention.As shown in FIG. 4, this embodiment is applicable to a PS domainhandover from an E-UTRAN to a UTRAN. The method for acquiring loadinformation in this embodiment may include the following steps:

Step 401: A source eNB to which a source cell belongs sends a HANDOVERREQUIRED (HANDOVER REQUIRED) message to an SGSN, where the HANDOVERREQUIRED message carries a first Transparent Container IE that carries asource cell load information IE.

Step 402: The SGSN receives the HANDOVER REQUIRED message and sends afirst RELOCATION REQUEST message to a target RNC to which a target cellbelongs, where the first RELOCATION REQUEST message carries the firstTransparent Container IE.

Step 403: The target RNC receives the first RELOCATION REQUEST messageand returns a RELOCATION REQUEST ACKNOWLEDGE message to the SGSN, wherethe RELOCATION REQUEST ACKNOWLEDGE message carries a second TransparentContainer IE that carries a target cell load information IE.

Step 404: The SGSN receives the RELOCATION REQUEST ACKNOWLEDGE messageand returns a first RELOCATION COMMAND message to the source eNB, wherethe first RELOCATION COMMAND message carries the second TransparentContainer IE.

In this embodiment, the first Transparent Container IE may be anInter-System Information Transparent Container IE or a Source RNC ToTarget RNC Transparent Container IE. Likewise, the second TransparentContainer IE may be an Inter-System Information Transparent Container IEor a Target RNC To Source RNC Transparent Container IE.

In this embodiment, the load information of different RAT systems isexchanged through the source cell load information IE carried in thefirst Transparent Container IE and the target cell load information IEcarried in the second Transparent Container IE. In this way, when aninter-RAT PS domain handover from the E-UTRAN to the UTRAN is performed,the E-UTRAN and the UTRAN can acquire load information of the peersystem, so that load balancing can be implemented between different RATsystems. Therefore, communications quality of the systems is guaranteed.

FIG. 5 is a schematic flowchart of a method for acquiring loadinformation according to a fifth embodiment of the present invention. Asshown in FIG. 5, this embodiment is applicable to a PS domain handoverfrom a GERAN to a UTRAN. The method for acquiring load information inthis embodiment may include the following steps:

Step 501: A source BSS to which a source cell belongs sends aPS-HANDOVER-REQUIRED (PS-HANDOVER-REQUIRED) message to an SGSN, wherethe PS-HANDOVER-REQUIRED message carries a first Transparent ContainerIE that carries a source cell load information IE.

Step 502: The SGSN receives the PS-HANDOVER-REQUIRED message and sends asecond RELOCATION REQUEST message to a target RNC to which a target cellbelongs, where the second RELOCATION REQUEST message carries the firstTransparent Container IE.

Step 503: The target RNC receives the second RELOCATION REQUEST messageand returns a RELOCATION REQUEST ACKNOWLEDGE message to the SGSN, wherethe RELOCATION REQUEST ACKNOWLEDGE message carries a second TransparentContainer IE that carries a target cell load information IE.

Step 504: The SGSN receives the RELOCATION REQUEST ACKNOWLEDGE messageand returns a first PS-HANDOVER-REQUIRED-ACK (PS-HANDOVER-REQUIRED-ACK)message to the source BSS, where the first PS-HANDOVER-REQUIRED-ACKmessage carries the second Transparent Container IE.

In this embodiment, the first Transparent Container IE may be anInter-System Information Transparent Container IE or a Source RNC ToTarget RNC Transparent Container IE. Likewise, the second TransparentContainer IE may be an Inter-System Information Transparent Container IEor a Target RNC To Source RNC Transparent Container IE.

In this embodiment, the load information of different RAT systems isexchanged through the source cell load information IE carried in thefirst Transparent Container IE and the target cell load information IEcarried in the second Transparent Container IE. In this way, when aninter-RAT PS domain handover from the GERAN to the UTRAN is performed,the GERAN and the UTRAN can acquire load information of the peer system,so that load balancing can be implemented between different RAT systems.Therefore, communications quality of the systems is guaranteed.

FIG. 6 is a schematic flowchart of a method for acquiring loadinformation according to a sixth embodiment of the present invention. Asshown in FIG. 6, this embodiment is applicable to a PS domain handoverfrom a GERAN to an E-UTRAN. The method for acquiring load information inthis embodiment may include the following steps:

Step 601: A source BSS to which a source cell belongs sends aPS-HANDOVER-REQUIRED message to an SGSN, where the PS-HANDOVER-REQUIREDmessage carries a first Transparent Container IE that carries a sourcecell load information IE.

Step 602: The SGSN receives the PS-HANDOVER-REQUIRED message and sends asecond HANDOVER REQUEST message to a target eNB to which a target cellbelongs, where the second HANDOVER REQUEST message carries the firstTransparent Container IE.

Step 603: The target eNB receives the second HANDOVER REQUEST messageand returns a HANDOVER REQUEST ACKNOWLEDGE message to the SGSN, wherethe HANDOVER REQUEST ACKNOWLEDGE message carries a second TransparentContainer IE that carries a target cell load information IE.

Step 604: The SGSN receives the HANDOVER REQUEST ACKNOWLEDGE message andreturns a second PS-HANDOVER-REQUIRED-ACK message to the source BSS,where the second PS-HANDOVER-REQUIRED-ACK message carries the secondTransparent Container IE.

In this embodiment, the first Transparent Container IE may be anInter-System Information Transparent Container IE or a Source eNB ToTarget eNB Transparent Container IE. Likewise, the second TransparentContainer IE may be an Inter-System Information Transparent Container IEor a Target eNB To Source eNB Transparent Container IE.

In this embodiment, the load information of different RAT systems isexchanged through the source cell load information IE carried in thefirst Transparent Container IE and the target cell load information IEcarried in the second Transparent Container IE. In this way, when aninter-RAT PS domain handover from the GERAN to the E-UTRAN is performed,the GERAN and the E-UTRAN can acquire load information of the peersystem, so that load balancing can be implemented between different RATsystems. Therefore, communications quality of the systems is guaranteed.

FIG. 7 is a schematic flowchart of a method for acquiring loadinformation according to a seventh embodiment of the present invention.As shown in FIG. 7, this embodiment is applicable to a PS domainhandover from an E-UTRAN to a GERAN. The method for acquiring loadinformation in this embodiment may include the following steps:

Step 701: A source eNB to which a source cell belongs sends a HANDOVERREQUIRED message to an SGSN, where the HANDOVER REQUIRED message carriesa first Transparent Container IE that carries a source cell loadinformation IE.

Step 702: The SGSN receives the HANDOVER REQUIRED message and sends asecond PS-HANDOVER-REQUEST message to a target BSS to which a targetcell belongs, where the second PS-HANDOVER-REQUEST message carries thefirst Transparent Container IE.

Step 703: The target BSS receives the second PS-HANDOVER-REQUEST messageand returns a PS-HANDOVER-REQUEST-ACKNOWLEDGE message to the SGSN, wherethe PS-HANDOVER-REQUEST-ACKNOWLEDGE message carries a second TransparentContainer IE that carries a target cell load information IE.

Step 704: The SGSN receives the PS-HANDOVER-REQUEST-ACKNOWLEDGE messageand returns a second HANDOVER COMMAND message to the source eNB, wherethe second HANDOVER COMMAND message carries the second TransparentContainer IE.

In this embodiment, the first Transparent Container IE may be anInter-System Information Transparent Container IE or a Source BSS ToTarget BSS Transparent Container IE. Likewise, the second TransparentContainer IE may be an Inter-System Information Transparent Container IEor a Target BSS To Source BSS Transparent Container IE.

In this embodiment, the load information of different RAT systems isexchanged through the source cell load information IE carried in thefirst Transparent Container IE and the target cell load information IEcarried in the second Transparent Container IE In this way, when aninter-RAT PS domain handover from the E-UTRAN to the GERAN is performed,the E-UTRAN and the GERAN can acquire load information of the peersystem, so that load balancing can be implemented between different RATsystems. Therefore, communications quality of the systems is guaranteed.

It should be noted that the above second to seventh embodiments of thepresent invention are all successful handover scenarios. Those skilledin the art may easily know that an embodiment of the present inventionmay also be a failed handover scenario, that is, the second TransparentContainer IE is carried in a response message that indicates a failure.Such a scenario is not further described herein.

In the methods for acquiring load information according to the first toseventh embodiments of the present invention, the source accesscontroller and the target access controller can exchange loadinformation only after the source access controller initiates a handoverrelated procedure. In this case, the target cell load informationacquired by the source access controller cannot avoid a failure of acurrent handover due to overload of the target access controller, butcan be used only as a guarantee of a next successful handover toimplement load balancing between different RAT systems so that thecommunications quality of the systems is guaranteed.

FIG. 8 is a flowchart of another method for acquiring load informationaccording to an eighth embodiment of the present invention. As shown inFIG. 8, the method for acquiring load information in this embodiment mayinclude the following steps:

Step 801: Before an inter-RAT handover is performed, a source accesscontroller to which a source cell belongs in a source RAT system sends,through a core network, an RIM based load information request message toa target access controller to which a target cell belongs in a targetRAT system.

Step 802: The source access controller receives an RIM based loadinformation response message returned by the target access controlleraccording to the RIM based load information request message through thecore network, where the RIM based load information response messagecarries load information of the target cell.

In this embodiment, the source RAT system and the target RAT systems maybe any two of a GERAN, a UTRAN, and an E-UTRAN. The corresponding accesscontrollers are respectively a BSS, an RNC, and an eNB.

In this embodiment, the source access controller may send the RIM basedload information request message to the target access controller in anevent-driven or periodical manner. For example, when the load of thesource cell exceeds 60%, the source cell reports a predetermined eventto its source access controller to drive the source access controller tosend an RIM based load information request message to the target accesscontroller through the core network; or the source access controller isdriven to send an RIM based load information request message to thetarget access controller through the core network at predeterminedintervals.

In this embodiment, the source access controller and the target accesscontroller may interact though the RIM based load information requestmessage and the RIM based load information response message, so that thesource RAT system acquires the load information of the target RAT systembefore an inter-RAT handover is performed. Therefore, load balancing canbe implemented between different RAT systems and communications qualityof the systems is guaranteed.

It should be noted that the number of target cells in the method foracquiring load information according to this embodiment may be one ormore than one. Specifically, the target cell or target cells can beindicated by carrying a cell ID of one target cell or a list of cell IDsof multiple target cells in the RIM based load information requestmessage. In the case of multiple target cells, after receiving an RIMbased load information request message that carries a list of cell IDsof multiple target cells, the core network locates the target accesscontroller of each target cell according to the target cell IDs in thelist of cell IDs. Each target access controller returns an RIM basedload information response message that carries load information of therespective target cell to the source access controller to which thesource cell belongs. The source access controller and the multipletarget access controllers interact though the RIM based load informationrequest message and RIM based load information response message, so thatthe source RAT system acquires the load information of multiple targetRAT systems before an inter-RAT handover is performed. In this way, atarget cell can be selected more effectively according to the loadinformation of multiple cells for implementing load balancing betweendifferent RAT systems. Therefore, the communications quality of thesystems is further guaranteed.

Because no interface is defined between the source access controller andthe target access controller, in this embodiment, the load informationrequest message and the load information response message can betransparently transmitted through an SGSN (PS domain) or a MobileSwitching Center (MSC, CS domain) in the core network.

Before An inter-RAT PS domain handover between any two of the precedingRAT systems is performed, the access controllers in different RATsystems each interact with the core network through different RIMrelated messages. The specific procedures are described in detail in thefollowing six exemplary embodiments of the present invention.

FIG. 9 is a schematic flowchart of another method for acquiring loadinformation according to a ninth embodiment of the present invention. Asshown in FIG. 9, this embodiment is applicable to a handover from aUTRAN to an E-UTRAN. The method for acquiring load information in thisembodiment may include the following steps:

Step 901: A source RNC to which a source cell belongs sends a firstDIRECT INFORMATION TRANSFER message to an SGSN or an MSC, where thefirst DIRECT INFORMATION TRANSFER message carries a first Inter-SystemInformation Transfer Type IE that carries a first RIM Transfer IE andthe first RIM Transfer IE carries a source cell load information IE.

Step 902: The SGSN or the MSC receives the first DIRECT INFORMATIONTRANSFER message and sends a first MME DIRECT INFORMATION TRANSFERmessage to a target eNB to which a target cell belongs, where the firstMME DIRECT INFORMATION TRANSFER message carries the first Inter-SystemInformation Transfer Type IE.

Step 903: The target eNB receives the first MME DIRECT INFORMATIONTRANSFER message and returns an eNB DIRECT INFORMATION TRANSFER messageto the SGSN or the MSC, where the eNB DIRECT INFORMATION TRANSFERmessage carries a second Inter-System Information Transfer Type IE thatcarries a second RIM Transfer IE and the second RIM Transfer IE carriesa target cell load information IE.

Step 904: The SGSN or the MSC receives the eNB DIRECT INFORMATIONTRANSFER message and returns a second DIRECT INFORMATION TRANSFERmessage to the source RNC, where the second DIRECT INFORMATION TRANSFERmessage carries the second Inter-System Information Transfer Type IE.

In this embodiment, the load information of different RAT systems isexchanged through the source cell load information IE carried in thefirst Transparent Container IE and the target cell load information IEcarried in the second Transparent Container IE. In this way, before aninter-RAT handover from the UTRAN to the E-UTRAN is performed, the UTRANand the E-UTRAN can acquire load information of the peer system, so thatload balancing can be implemented between different RAT systems.Therefore, communications quality of the systems is guaranteed.

FIG. 10 is a schematic flowchart of another method for acquiring loadinformation according to a tenth embodiment of the present invention. Asshown in FIG. 10, this embodiment is applicable to a handover from aUTRAN to a GERAN. The method for acquiring load information in thisembodiment may include the following steps:

Step 1001: A source RNC to which a source cell belongs sends a firstDIRECT INFORMATION TRANSFER message to an SGSN or an MSC, where thefirst DIRECT INFORMATION TRANSFER message carries a first Inter-SystemInformation Transfer Type IE that carries a first RIM Transfer IE andthe first RIM Transfer IE carries a source cell load information IE.

Step 1002: The SGSN or the MSC receives the first DIRECT INFORMATIONTRANSFER message and sends a first RIM-PDU-TRANSFER.req message to atarget BSS to which a target cell belongs, where the firstRIM-PDU-TRANSFER.req message carries a first RIM Container IE thatcarries a source cell load information IE.

Step 1003: The target BSS receives the first RIM-PDU-TRANSFER.reqmessage and returns a first RIM-PDU-TRANSFER.ind message to the SGSN orthe MSC, where the first RIM-PDU-TRANSFER.ind message carries a secondRIM Container IE that carries a target cell load information IE.

Step 1004: The SGSN or the MSC receives the first RIM-PDU-TRANSFER.indmessage and returns a third DIRECT INFORMATION TRANSFER message to thesource RNC, where the third DIRECT INFORMATION TRANSFER message carriesa third Inter-System Information Transfer Type IE that carries a thirdRIM Transfer IE and the third RIM Transfer IE carries a target cell loadinformation IE.

In this embodiment, the first RIM-PDU-TRANSFER.req message may include aRAN-INFORMATION-REQUEST PDU message; the first RIM-PDU-TRANSFER.indmessage may include a RAN-INFORMATION PDU message.

In this embodiment, the load information of different systems isexchanged by carrying the source cell load information IE in the firstRIM Transfer IE and the first RIM Container IE and carrying the targetcell load information IE in the second RIM Container IE and the secondRIM Transfer IE. In this way, before an inter-RAT handover from theUTRAN to the GERAN is performed, the UTRAN and the GERAN can acquireload information of the peer system, so that load balancing can beimplemented between different RAT systems. Therefore, communicationsquality of the systems is guaranteed.

FIG. 11 is a schematic flowchart of another method for acquiring loadinformation according to an eleventh embodiment of the presentinvention. As shown in FIG. 11, this embodiment is applicable to ahandover from an E-UTRAN to a UTRAN. The method for acquiring loadinformation in this embodiment may include the following steps:

Step 1101: A source eNB to which a source cell belongs sends an eNBDIRECT INFORMATION TRANSFER message to an SGSN or and MSC, where the eNBDIRECT INFORMATION TRANSFER message carries a second Inter-SystemInformation Transfer Type IE that carries a second RIM Transfer IE andthe second RIM Transfer IE carries a source cell load information IE.

Step 1102: The SGSN or the MSC receives the eNB DIRECT INFORMATIONTRANSFER message and sends a second DIRECT INFORMATION TRANSFER messageto a target RNC to which a target cell belongs, where the second DIRECTINFORMATION TRANSFER message carries the second Inter-System InformationTransfer Type IE.

Step 1103: The target RNC receives the second DIRECT INFORMATIONTRANSFER message and returns a first DIRECT INFORMATION TRANSFER messageto the SGSN or the MSC, where the first DIRECT INFORMATION TRANSFERmessage carries a first Inter-System Information Transfer Type IE thatcarries a first RIM Transfer IE and the first RIM Transfer IE carries atarget cell load information IE.

Step 1104: The SGSN or the MSC receives the first DIRECT INFORMATIONTRANSFER message and returns a first MME DIRECT INFORMATION TRANSFERmessage to the source eNB, where the first MME DIRECT INFORMATIONTRANSFER message carries the first Inter-System Information TransferType IE.

In this embodiment, the load information of different RAT systems isexchanged through the source cell load information IE carried in thefirst Transparent Container IE and the target cell load information IEcarried in the second Transparent Container IE. In this way, before aninter-RAT handover from the E-UTRAN to the UTRAN is performed, theE-UTRAN and the UTRAN can acquire load information of the peer system,so that load balancing can be implemented between different RAT systems.Therefore, communications quality of the systems is guaranteed.

FIG. 12 is a schematic flowchart of another method for acquiring loadinformation according to a twelfth embodiment of the present invention.As shown in FIG. 12, this embodiment is applicable to a handover from aGERAN to a UTRAN. The method for acquiring load information in thisembodiment may include the following steps:

Step 1201: A source BSS to which a source cell belongs sends a secondRIM-PDU-TRANSFER.req message to an SGSN or an MSC, where the secondRIM-PDU-TRANSFER.req message carries a third RIM Container IE thatcarries a source cell load information IE.

Step 1202: The SGSN or the MSC receives the second RIM-PDU-TRANSFER.reqmessage and sends a third DIRECT INFORMATION TRANSFER message to atarget RNC to which a target cell belongs, where the third DIRECTINFORMATION TRANSFER message carries a third Inter-System InformationTransfer Type IE that carries a third RIM Transfer IE and the third RIMTransfer IE further carries a source cell load information IE.

Step 1203: The target RNC receives the third DIRECT INFORMATION TRANSFERmessage and returns a first DIRECT INFORMATION TRANSFER message to theSGSN or the MSC, where the first DIRECT INFORMATION TRANSFER messagecarries a first Inter-System Information Transfer Type IE that carries afirst RIM Transfer IE and the first RIM Transfer IE carries a targetcell load information IE.

Step 1204: The SGSN or the MSC receives the first DIRECT INFORMATIONTRANSFER message and returns a second RIM-PDU-TRANSFER.ind message tothe source BSS, where the second RIM-PDU-TRANSFER.ind message carries afourth RIM Container IE that carries a target cell load information IE.

In this embodiment, the second RIM-PDU-TRANSFER.req message may includea RAN-INFORMATION-REQUEST PDU message; the second RIM-PDU-TRANSFER.indmessage may include a RAN-INFORMATION PDU message.

In this embodiment, the load information of different systems isexchanged by carrying the source cell load information IE in the thirdRIM Container IE and the third RIM Transfer IE and carrying the targetcell load information IE in the first RIM Transfer IE and the fourth RIMContainer IE. In this way, before an inter-RAT handover from the GERANto the UTRAN is performed, the GERAN and the UTRAN can acquire loadinformation of the peer system, so that load balancing can beimplemented between different RAT systems. Therefore, communicationsquality of the systems is guaranteed.

FIG. 13 is a schematic flowchart of another method for acquiring loadinformation according to a thirteenth embodiment of the presentinvention. As shown in FIG. 13, this embodiment is applicable to ahandover from a GERAN to an E-UTRAN. The method for acquiring loadinformation in this embodiment may include the following steps:

Step 1301: A source BSS to which a source cell belongs sends a secondRIM-PDU-TRANSFER.req message to an SGSN or an MSC, where the secondRIM-PDU-TRANSFER.req message carries a third RIM Container IE thatcarries a source cell load information IE.

Step 1302: The SGSN or the MSC receives the second RIM-PDU-TRANSFER.reqmessage and sends a second MME DIRECT INFORMATION TRANSFER message to atarget eNB to which a target cell belongs, where the second MME DIRECTINFORMATION TRANSFER message carries a third Inter-System InformationTransfer Type IE that carries a third RIM Transfer IE and the third RIMTransfer IE further carries a source cell load information IE.

Step 1303: The target eNB receives the second MME DIRECT INFORMATIONTRANSFER message and returns an eNB DIRECT INFORMATION TRANSFER messageto the SGSN or the MSC, where the eNB DIRECT INFORMATION TRANSFERmessage carries a second Inter-System Information Transfer Type IE thatcarries a second RIM Transfer IE and the second RIM Transfer IE carriesa target cell load information IE.

Step 1304: The SGSN or the MSC receives the eNB DIRECT INFORMATIONTRANSFER message and returns a third RIM-PDU-TRANSFER.ind message to thesource BSS, where the third RIM-PDU-TRANSFER.ind message carries a fifthRIM Container IE that carries a target cell load information IE.

In this embodiment, the second RIM-PDU-TRANSFER.req message may includea RAN-INFORMATION-REQUEST PDU message; the third RIM-PDU-TRANSFER.indmessage may include a RAN-INFORMATION PDU message.

In this embodiment, the load information of different systems isexchanged by carrying the source cell load information IE in the thirdRIM Container IE and the third RIM Transfer IE and carrying the targetcell load information IE in the second RIM Transfer IE and the fifth RIMContainer IE. In this way, before an inter-RAT handover from the GERANto the E-UTRAN is performed, the GERAN and the E-UTRAN can acquire loadinformation of the peer system, so that load balancing can beimplemented between different RAT systems. Therefore, communicationsquality of the systems is guaranteed.

FIG. 14 is a schematic flowchart of another method for acquiring loadinformation according to a fourteenth embodiment of the presentinvention. As shown in FIG. 14, this embodiment is applicable to ahandover from an E-UTRAN to a GERAN. The method for acquiring loadinformation in this embodiment may include the following steps:

Step 1401: A source eNB to which a source cell belongs sends an eNBDIRECT INFORMATION TRANSFER message to an SGSN or an MSC, where the eNBDIRECT INFORMATION TRANSFER message carries a second Inter-SystemInformation Transfer Type IE that carries a second RIM Transfer IE andthe second RIM Transfer IE further carries a source cell loadinformation IE.

Step 1402: The SGSN or the MSC receives the eNB DIRECT INFORMATIONTRANSFER message and sends a third RIM-PDU-TRANSFER.req message to atarget BSS to which a target cell belongs, where the thirdRIM-PDU-TRANSFER.req message carries a sixth RIM Container IE thatcarries a source cell load information IE.

Step 1403: The target BSS receives the third RIM-PDU-TRANSFER.reqmessage and returns a first RIM-PDU-TRANSFER.ind message to the SGSN orthe MSC, where the first RIM-PDU-TRANSFER.ind message carries a secondRIM Container IE that carries a target cell load information IE.

Step 1404: The SGSN or MSC receives the first RIM-PDU-TRANSFER.indmessage and returns a second MME DIRECT INFORMATION TRANSFER message tothe source eNB, where the second MME DIRECT INFORMATION TRANSFER messagecarries a third Inter-System Information Transfer Type IE that carries athird RIM Transfer IE and the third RIM Transfer IE further carries atarget cell load information IE.

In this embodiment, the third RIM-PDU-TRANSFER.req message may include aRAN-INFORMATION-REQUEST PDU message; the first RIM-PDU-TRANSFER.indmessage may include a RAN-INFORMATION PDU message.

In this embodiment, the load information of different systems isexchanged by carrying the source cell load information IE in the secondRIM Transfer IE and the sixth RIM Container IE and carrying the targetcell load information IE in the second RIM Container ID and the thirdRIM Transfer IE. In this way, before an inter-RAT handover from theE-UTRAN to the GETRAN is performed, the E-UTRAN and the GERAN canacquire load information of the peer system, so that load balancing canbe implemented between different RAT systems. Therefore, communicationsquality of the systems is guaranteed.

In the methods for acquiring load information according to the eighth tofourteenth embodiments of the present invention, load information isobtained between the source access controller and the target accesscontroller before the source access controller initiates a handoverrelated procedure. In this case, the target cell load informationacquired by the source access controller can be a guarantee of successof a current handover and help to effectively avoid a failure of thecurrent handover due to overload of the target access controller.Therefore, load balancing between different RAT systems can beimplemented to guarantee the communications quality of the systems.

It should be noted that for a description purpose, the foregoingembodiments of the present invention are all described as a series ofactions, but those skilled in the art may understand that the presentinvention is not limited to a sequence of actions described herein andthat according to the present invention, some steps may be performed inother sequences or at the same time. Those skilled in the art may alsounderstand that the embodiments described herein are only some exemplaryembodiments of the present invention and that the actions and modulesconcerned may not be mandatory in the present invention.

In the foregoing embodiments of the present invention, each embodimenthas its emphasis. What is not detailed in one embodiment of the presentinvention is detailed in the related description of another embodiment.

FIG. 15 is a schematic structural diagram of an access controlleraccording to a fifteenth embodiment of the present invention. As shownin FIG. 15, the access controller in this embodiment may include a firstsending module 151 and a first receiving module 152. The first sendingmodule 151 is configured to send, through a core network, an inter-RAThandover request message to a target access controller to which a targetcell belongs when an inter-RAT PS domain handover is performed; thefirst receiving module 152 is configured to receive an inter-RAThandover response message returned by the target access controlleraccording to the inter-RAT handover request message through the corenetwork, where the inter-RAT handover response message carries loadinformation of the target cell.

The source access controller in the first embodiment of the presentinvention, the source RNC in the second embodiment of the presentinvention, the source RNC in the third embodiment of the presentinvention, the source eNB in the fourth embodiment of the presentinvention, the source BSS in the fifth embodiment of the presentinvention, the source BSS in the sixth embodiment of the presentinvention, and the source eNB in the seventh embodiment of the presentinvention may all be implemented by the access controller provided inthis embodiment.

FIG. 16 is a schematic structural diagram of another access controlleraccording to a sixteenth embodiment of the present invention. As shownin FIG. 16, the access controller in this embodiment includes a secondreceiving module 161 and a second sending module 162. The secondreceiving module 161 is configured to receive, through a core network,an inter-RAT handover request message sent by a source access controllerto which a source cell belongs; the second sending module 162 isconfigured to return an inter-RAT handover response message to thesource access controller through the core network, where the inter-RAThandover response message carries load information of a target cellserved by the access controller in this embodiment of the presentinvention.

The target access controller in the first embodiment of the presentinvention, the target eNB in the second embodiment of the presentinvention, the target BSS in the third embodiment of the presentinvention, the target RNC in the fourth embodiment of the presentinvention, the target RNC in the fifth embodiment of the presentinvention, the target eNB in the sixth embodiment of the presentinvention, and the target BSS in the seventh embodiment of the presentinvention may all be implemented by the access controller provided inthis embodiment.

FIG. 17 is a schematic structural diagram of still another accesscontroller according to a seventeenth embodiment of the presentinvention. As shown in FIG. 17, the access controller in the embodimentof the present invention may include a third sending module 171 and athird receiving module 172. The third sending module 171 is configuredto send, through a core network, an RIM based load information requestmessage to a target access controller to which a target cell belongsbefore an inter-RAT handover is performed; the third receiving module172 is configured to receive an RIM based load information responsemessage returned by the target access controller according to the RIMbased load information request message through the core network, wherethe RIM based load information response message carries load informationof the target cell.

The source access controller in the eighth embodiment of the presentinvention, the source RNC in the ninth embodiment of the presentinvention, the source RNC in the tenth embodiment of the presentinvention, the source eNB in the eleventh embodiment of the presentinvention, the source BSS in the twelfth embodiment of the presentinvention, the source BSS in the thirteenth embodiment of the presentinvention, and the source eNB in the fourteenth embodiment of thepresent invention may all be implemented by the access controllerprovided in this embodiment.

FIG. 18 is a schematic structural diagram of still another accesscontroller according to an eighteenth embodiment of the presentinvention. As shown in FIG. 18, the access controller in this embodimentmay include a fourth receiving module 181 and a fourth sending module182. The fourth receiving module 181 is configured to receive an RIMbased load information request message that is sent, through a corenetwork, by a source access controller to which a source cell belongs;the fourth sending module 182 is configured to return an RIM based loadinformation response message to the source access controller through thecore network, where the RIM based load information response messagecarries load information of a target cell served by the accesscontroller provided in this embodiment of the present invention.

The target access controller in the eighth embodiment of the presentinvention, the target eNB in the ninth embodiment of the presentinvention, the target BSS in the tenth embodiment of the presentinvention, the target RNC in the eleventh embodiment of the presentinvention, the target RNC in the twelfth embodiment of the presentinvention, the target eNB in the thirteenth embodiment of the presentinvention, and the target BSS in the fourteenth embodiment of thepresent invention may all be implemented by the access controllerprovided in this embodiment.

FIG. 19 is a schematic structural diagram of a system for acquiring loadinformation according to a nineteenth embodiment of the presentinvention. As shown in FIG. 19, the system for acquiring loadinformation in this embodiment may include a first source accesscontroller 10 to which a source cell belongs in a source RAT system anda first target access controller 20 to which a target cell belongs in atarget RAT system.

The first source access controller 10 is configured to send, through acore network, an inter-RAT handover request message to the first targetaccess controller 20 to which the target cell belongs when an inter-RATPS domain handover is performed, and configured to receive an inter-RAThandover response message returned by the first target access controller20 through the core network, where the inter-RAT handover responsemessage carries load information of the target cell.

The first target access controller 20 is configured to receive theinter-RAT handover request message that is sent, through the corenetwork, by the first source access controller 10 to which the sourcecell belongs, and configured to return the inter-RAT handover responsemessage to the first source access controller 10 through the corenetwork.

The source access controller in the first embodiment of the presentinvention, the source RNC in the second embodiment of the presentinvention, the source RNC in the third embodiment of the presentinvention, the source eNB in the fourth embodiment of the presentinvention, the source BSS in the fifth embodiment of the presentinvention, the source BSS in the sixth embodiment of the presentinvention, and the source eNB in the seventh embodiment of the presentinvention may all be implemented by the first source access controller10 in the system for acquiring load information in this embodiment; thetarget access controller in the first embodiment of the presentinvention, the target eNB in the second embodiment of the presentinvention, the target BSS in the third embodiment of the presentinvention, the target RNC in the fourth embodiment of the presentinvention, the target RNC in the fifth embodiment of the presentinvention, the target eNB in the sixth embodiment of the presentinvention, and the target BSS in the seventh embodiment of the presentinvention may all be implemented by the first target access controller20 in the system for acquiring load information in this embodiment.

In this embodiment, the source access controller and the target accesscontroller may interact through inter-RAT handover related messages. Inthis way, when an inter-RAT PS domain handover is performed, the sourceRAT system can acquire load information of the target RAT system, sothat load balancing can be implemented between different RAT systems.Therefore, communications quality of the systems can be guaranteed.

FIG. 20 is a schematic structural diagram of another system foracquiring load information according to a twentieth embodiment of thepresent invention. As shown in FIG. 20, the system for acquiring loadinformation in this embodiment may include a second source accesscontroller 30 to which a source cell belongs in a source RAT system anda second target access controller 40 to which a target cell belongs in atarget RAT system.

The second source access controller 30 is configured to send, through acore network, an RIM based load information request message to thesecond target access controller 40 to which the target cell belongsbefore an inter-RAT handover is performed, and configured to receive anRIM based load information response message returned by the secondtarget access controller 40 through the core network, where the RIMbased load information response message carries load information of thetarget cell.

The second target access controller 40 is configured to receive the RIMbased load information request message that is sent, through the corenetwork, by the second source access controller 30 to which the sourcecell belongs, and configured to return the RIM based load informationresponse message to the second source access controller 30 through thecore network.

The source access controller in the eighth embodiment of the presentinvention, the source RNC in the ninth embodiment of the presentinvention, the source RNC in the tenth embodiment of the presentinvention, the source eNB in the eleventh embodiment of the presentinvention, the source BSS in the twelfth embodiment of the presentinvention, the source BSS in the thirteenth embodiment of the presentinvention, and the source eNB in the fourteenth embodiment of thepresent invention may all be implemented by the second source accesscontroller 30 in the system for acquiring load information in thisembodiment; the target access controller in the eighth embodiment of thepresent invention, the target eNB in the ninth embodiment of the presentinvention, the target BSS in the tenth embodiment of the presentinvention, the target RNC in the eleventh embodiment of the presentinvention, the target RNC in the twelfth embodiment of the presentinvention, the target eNB in the thirteenth embodiment of the presentinvention, and the target BSS in the fourteenth embodiment of thepresent invention may all be implemented by the second target accesscontroller 40 in the system for acquiring load information in thisembodiment.

In this embodiment, the source access controller and the target accesscontroller may interact though the RIM based load information requestmessage and the RIM based load information response message, so that thesource RAT system acquires the load information of the target RAT systembefore an inter-RAT handover is performed. In this way, load balancingcan be implemented between different RAT systems and communicationsquality of the systems can be guaranteed.

Those skilled in the art may understand that all or a portion of thesteps in the methods of the embodiments of the present invention may beimplemented by hardware under the instruction of a program. The programmay be stored in a computer readable storage medium and when the programis executed, the steps in the methods of the embodiments of the presentinvention are executed. The storage medium may be any medium that canstore program codes, such as a Read Only Memory (Read Only Memory, ROM),a Random Access Memory (RAM), a magnetic disk, or a Compact Disk-ReadOnly Memory (CD-ROM).

Although the present invention is described in detail through someexemplary embodiments, the present invention is not limited to suchembodiments. It is apparent that those skilled in the art may makevarious modifications and variations to the present invention withoutdeparting from the spirit and scope of the present invention. Thepresent invention is intended to cover the modifications and variationsprovided that they fall within the scope of protection defined by theclaims or their equivalents.

What is claimed is:
 1. A method for acquiring load information, themethod is applicable to a PS domain handover from an E-UTRAN to a UTRAN,comprising: sending, by a source eNB to which a source cell belongs, ahandover request to an SGSN, so that a first relocation request messageis sent from the SGSN to a target RNC to which a target cell belongs;receiving, by the source eNB, a first relocation command message fromthe SGSN, wherein the first relocation command message is returned bythe SGSN according to an first relocation request acknowledge messagereturned by the target RNC; wherein the handover request message carriesa first transparent container IE that carries a source cell loadinformation IE; wherein the first relocation request message carries thefirst transparent container IE; wherein the first relocation requestacknowledge message carries a second transparent container IE thatcarries a target cell load information; wherein the first relocationcommand message carries the second transparent container IE.
 2. Themethod of claim 1, wherein the first transparent container IE comprisesan inter-system information transparent container IE and/or a source RNCto target RNC transparent container IE; and the second transparentcontainer IE comprises an inter-system information transparent containerIE and/or a target RNC to source RNC transparent Container IE.
 3. Amethod for acquiring load information, the method is applicable to a PSdomain handover from an UTRAN to an E-UTRAN, comprising: sending, by asource RNC to which a source cell belongs, a relocation required messageto a SGSN, so that a first handover request message is sent from theSGSN to a target eNB to which a target cell belongs; receiving, by thesource RNC, a first relocation command message from the SGSN, whereinthe first relocation command message is returned by the SGSN accordingto the first relocation request acknowledge message returned by thetarget eNB; wherein the relocation required message carries a firsttransparent container IE that carries a source cell load information IE;wherein the first handover request message carries the first transparentcontainer IE; wherein the handover request acknowledge carries a secondtransparent container IE that carries a target cell load information IE;wherein the first relocation command message carries the secondtransparent container IE.
 4. The method of claim 3, wherein the firsttransparent container IE comprises an inter-system informationtransparent container IE or a source eNB to target eNB transparentcontainer IE; and the second transparent container IE comprises aninter-system information transparent container IE or a target eNB tosource eNB transparent container IE.
 5. A method for acquiring loadinformation, the method is applicable to a PS domain handover from anE-UTRAN to a UTRAN, comprising: receiving, by a target RNC to which asource cell belongs, a first relocation request message, wherein thefirst relocation request is sent from a SGSN according to a handoverrequest sent by a source eNB; sending, by the target RNC, a relocationrequest acknowledge message to the SGSN, so that the SGSN returns afirst relocation command message to the source eNB, wherein the firstrelocation command message is returned by the SGSN according to an firstrelocation request acknowledge message returned by the target RNC;wherein the handover request message carries a first transparentcontainer IE that carries a source cell load information IE; wherein thefirst relocation request message carries the first transparent containerIE; wherein the first relocation request acknowledge message carries asecond transparent container IE that carries a target cell loadinformation; wherein the first relocation command message carries thesecond transparent container IE.
 6. The method of claim 5, wherein thefirst transparent container IE comprises an inter-system informationtransparent container IE and/or a source RNC to target RNC transparentcontainer IE; and the second transparent container IE comprises aninter-system information transparent container IE and/or a target RNC tosource RNC transparent Container IE.
 7. A method for acquiring loadinformation, the method is applicable to a PS domain handover from aUTRAN to an E-UTRAN, comprising: receiving, by a target eNB to which atarget cell belongs, a first handover request message from a SGSN,wherein the first handover request message is sent from the SGSNaccording to a relocation required message sent by a source RNC;sending, by the target eNB, a handover request acknowledge message tothe SGSN, so that the SGSN returned a first relocation command messageto the source RNC; wherein the relocation required message carries afirst transparent container IE that carries a source cell loadinformation IE; wherein the first handover request message carries thefirst transparent container IE; wherein the handover request acknowledgecarries a second transparent container IE that carries a target cellload information IE; wherein the first relocation command messagecarries the second transparent container IE.
 8. The method of claim 7,wherein the first transparent container IE comprises an inter-systeminformation transparent container IE or a source eNB to target eNBtransparent container IE; and the second transparent container IEcomprises an inter-system information transparent container IE or atarget eNB to source eNB transparent container IE.
 9. An apparatus foracquiring load information, the apparatus which a source cell belongs,the apparatus is applicable to a PS domain handover from an E-UTRAN to aUTRAN, comprising: a transmitter, configured to send a handover requestto an SGSN, so that a first relocation request message is sent from theSGSN to a target RNC to which a target cell belongs; a receiver,configured to receive a first relocation command message from the SGSN,wherein the first relocation command message is returned by the SGSNaccording to an first relocation request acknowledge message returned bythe target RNC; wherein the handover request message carries a firsttransparent container IE that carries a source cell load information IE;wherein the first relocation request message carries the firsttransparent container IE; wherein the first relocation requestacknowledge message carries a second transparent container IE thatcarries a target cell load information; wherein the first relocationcommand message carries the second transparent container IE.
 10. Theapparatus of claim 9, wherein the first transparent container IEcomprises an inter-system information transparent container IE and/or asource RNC to target RNC transparent container IE; and the secondtransparent container IE comprises an inter-system informationtransparent container IE and/or a target RNC to source RNC transparentContainer IE.
 11. An apparatus for acquiring load information, theapparatus which a source cell belongs, the apparatus is applicable to aPS domain handover from an E-UTRAN to a UTRAN, comprising: atransmitter, configured to send a relocation required message to a SGSN,so that a first handover request message is sent from the SGSN to atarget eNB to which a target cell belongs; a receiver, configured toreceive first relocation command message from the SGSN, wherein thefirst relocation command message is returned by the SGSN according tothe first relocation request acknowledge message returned by the targeteNB; wherein the relocation required message carries a first transparentcontainer IE that carries a source cell load information IE; wherein thefirst handover request message carries the first transparent containerIE; wherein the handover request acknowledge carries a secondtransparent container IE that carries a target cell load information IE;wherein the first relocation command message carries the secondtransparent container IE.
 12. The apparatus of claim 11, wherein thefirst transparent container IE comprises an inter-system informationtransparent container IE or a source eNB to target eNB transparentcontainer IE; and the second transparent container IE comprises aninter-system information transparent container IE or a target eNB tosource eNB transparent container IE.
 13. An apparatus for acquiring loadinformation, the apparatus which a source cell belongs, the apparatus isapplicable to a PS domain handover from an E-UTRAN to a UTRAN,comprising: a receiver, configured to receive a first relocation requestmessage, wherein the first relocation request is sent from a SGSNaccording to a handover request sent by a source eNB; a transmitter,configured to send a relocation request acknowledge message to the SGSN,so that the SGSN returns a first relocation command message to thesource eNB, wherein the first relocation command message is returned bythe SGSN according to an first relocation request acknowledge messagereturned by the target RNC; wherein the handover request message carriesa first transparent container IE that carries a source cell loadinformation IE; wherein the first relocation request message carries thefirst transparent container IE; wherein the first relocation requestacknowledge message carries a second transparent container IE thatcarries a target cell load information; wherein the first relocationcommand message carries the second transparent container IE.
 14. Theapparatus of claim 13, wherein the first transparent container IEcomprises an inter-system information transparent container IE and/or asource RNC to target RNC transparent container IE; and the secondtransparent container IE comprises an inter-system informationtransparent container IE and/or a target RNC to source RNC transparentContainer IE.
 15. An apparatus for acquiring load information, theapparatus which a target cell belongs, the apparatus is applicable to aPS domain handover from an E-UTRAN to a UTRAN, comprising: a receiver,configured to receive a first handover request message from a SGSN,wherein the first handover request message is sent from the SGSNaccording to a relocation required message sent by a source RNC; atransmitter, configured to send a handover request acknowledge messageto the SGSN, so that the SGSN returned a first relocation commandmessage to the source RNC; wherein the relocation required messagecarries a first transparent container IE that carries a source cell loadinformation IE; wherein the first handover request message carries thefirst transparent container IE; wherein the handover request acknowledgecarries a second transparent container IE that carries a target cellload information IE; wherein the first relocation command messagecarries the second transparent container IE.
 16. The apparatus of claim15, wherein the first transparent container IE comprises an inter-systeminformation transparent container IE or a source eNB to target eNBtransparent container IE; and the second transparent container IEcomprises an inter-system information transparent container IE or atarget eNB to source eNB transparent container IE.